Stuart Kuhn
Photography
Eva Krupp
"Stuart Kuhn approached me with a very interesting and unusual request: to extract mercury from a marine mammal, and to use the mercury to make a daguerreotype picture using this mercury. I was intrigued by this project and agreed to help him in his highly unusual quest.
We started by setting up the daguerreotype photography, and Stuart had built bespoke material to realise this. The setup worked successfully, and so we went further on the produce elemental mercury from mercury solutions. This was challenging but could be realised. The final step was to obtain samples from a marine mammal, which we realised in cooperation with the Scottish stranding scheme: 7 kg of liver and 4 kg of kidney were obtained from a stranded dolphin, and we prepared this for mercury extraction.
This was a very difficult task, and unluckily, the same approach as with the mercury solutions was not successful to produce and extract elemental mercury. Several options were followed, but we still have to find the right method.
It has been a huge pleasure to be involved in this project. Stuart has been very committed, and learned a lot of chemistry in the process. His idea of combining chemistry, photography and environmental issues is unique and we will continue trying to find a method to finalise this project in full."
Cornelius Brombach, PhD student at University of Aberdeen
"Photographer Stuart Kuhn came up with a photographical project which involved the extraction of elemental mercury from marine animals and to use it for the development of a daguerreotype.
He contacted the University of Aberdeen for the assistance in the extraction procedure of elemental mercury and Dr Eva Krupp was instantly fascinated by the interdisciplinary task and the art idea behind it. Stuart visited the University of Aberdeen for 6 weeks in Spring 2014 and started working on the project. I was assigned to Stuart for the chemistry support. The main challenge was the transformation of organic mercury (e.g. MeHg+) and divalent mercury (Hg2+), the main mercury species in living organisms, into elemental, silvery mercury (Hg0). Andrew Brownlow from the Scottish Marine Animal Stranding Scheme kindly provided 5 kg of a dolphin liver. We did first a spike experiment to save the rare dolphin liver sample. 200 g of a lamb liver was therefore purchased from a local supermarket, spiked with divalent mercury and then boiled in 500 mL concentrated nitric acid for 2 hours to dissolve the sample. 100 mL Hydrogen peroxide was then added and the solution boiled for another 1 hour. The clear, yellow coloured solution was then diluted with water to 2 L and copper sheets were then placed in the solution overnight. During the night, the divalent mercury had reacted with the copper and deposited as a silver layer on top of the copper sheet. This elemental mercury was then heated of from the copper sheets and trapped in a cool finger as a small droplet of elemental mercury.
The dolphin liver contained 60 mg/kg mercury and therefore, 1 kg of dolphin liver was digested in 3 L nitric acid, to obtain ideally a droplet of 60 mg mercury. 500 mL hydrogen peroxide was added after an hour and the solution boiled for one further hour. The solution left standing for cooling down; the fat was filtered off to obtain a clear, yellow solution. The solution was then diluted to a final volume of 10 L and the copper sheets were placed in the solution overnight. No visible deposition of elemental mercury occurred. One possible reason is the higher matrix in the dolphin liver digest compared to the lamb liver digest. We tried several other routes:
(1) Direct reduction of the divalent mercury in the solution and the purging of the elemental mercury from the sample and trapping in a cool finger
(2) The trapping of the divalent mercury on a sulphur material and the subsequent elution, which allowed the loss of the matrix
But none of the routes led to a droplet of elemental mercury so far.
The project was an interesting challenge and still requires some work. Seeing a daguerreotype made from commercially available elemental mercury by Stuart Kuhn fascinated me and I would love to see some daguerreotypes done with elemental mercury obtained from marine animals to show the pollution of our environment with mercury in a different, artistic way compared to concentrations out of an analyser."